Also, i forgot -

In the third round of breeding: 100% het. Male x 50% Het. Female -
It would be possible that all of the offspring appear normal, thus making them 66% het. Hopefully you could get lucky and get a dominant carrier out of the breeding, but i'd recommend trying to breed to multiple normal females in the first round, and thus upping your odds of hitting a dominant in the proving process(just due to more eggs being produced....you're giving yourself more chances)